Am I being a bitch?

So went to the doctors today for my son, he's 2 and I had him on the counter. I go to pull him off the counter to go sit down in the waiting area and his leg knocks of a stapler. It was 7am, I'm exhausted, and when I'm tired I usually have RBFS. I looked at my son to see if he was ok, duh* it's a hard object and he was fine. This guy across from me says "don't you blame that baby for what you did" in a joking tone and laughs. I guess maybe my hand brushed it too at first, but then I realized this guy was just joking at my expense. Everyone behind the counter, which was about 5 people, laughed and looked at me. I was not amused, and just picked up the stapler and sat down thinking what pricks they were. It was on the other side of my child, how the hell would he know who's body knocked it off? He wouldn't. He completely embarrassed me like I blame my son for accidents. This was a patient btw, not a nurse. My mom calls and thinks I'm being bitchy. Am I? I did not find it funny!